Processing Hypertext Links after XLink

The W3C’s XML Linking Language (XLink) offers hypertext linking capabilities exceeding those known from the Hypertext Markup Language (HTML) by far. XLink’s biggest contribution is to allow out-of-line links. These are not defined at a link’s source or destination, but in a linkbase separate from the documents they link. However, XLink and related standards leave many questions open. After reviewing some of these questions, two are looked at closer and extensions to XLink are proposed as solutions. The first contribution is the introduction of interfaces as link participants. These interfaces give well-defined access points to link structures and ease reuse and combination of link structures. They provide a kind of symbolic address and can also be used to decouple documents from their physical location. The second contribution is the suggestion of linkbase management mechanism. Linkbase management is concerned with finding external linkbases and deciding which links are to be displayed. As an extension to XLink, the linkbase management mechanism introduces three linkbase arcs. The arcs allow a linkbase to be applied to the current document only, to a limited range of documents, or to all documents.